Tire valve steam assembly



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E. EGER ETAL TIRE VALVE STEM ASSEMBLY Original Filed March 18, 1939 I INVENTOR ERNST E6 v RAYMOND R TERNES ATTORNEY Patented July 8, 1941 warren STATES I PATENT orric- Ernst Eger, Grosse Pointe Park, and Raymond F. Ternes, Detroit, Mich assignors to United States Rubber Company, New York, N. Y., a corporation of New Jersey Original application March 18, 1939, Serial No. 262,694. Divided and this application April 2, 1941, Serial No. 386,440

1 Claim. (o 152-427) This invention relates to a valve stem and cap assembly as applied to pneumatic tires, and in particular it relates to a valve stem and cap having a layer of rubber composition completely covering the exterior thereof. In valve stems, particularly for heavy service tires, it is customary to use a type of stem which is flexible or bendable in order that it may conform with various types of wheel assemblies. Because of small rim diameters of tires and the relatively large diameter of brake drums, very little clearance is provided in each instance for the valve stem. As a result, it frequently occurs that the valve stem, and particularly the conventional metal valve stem cap, rests upon the brake drum or upon other metal parts directly connected to the brake drum. The brake drums on trucks and busses encounter relatively high temperatures during the operation of the vehicle. When any metal part of the valve stem or cap rests against the brake drum or associated parts the heat therefrom is transmitted through the metal valve cap and to the valve mechanism located within the stem.

Most valve mechanisms are provided with a rubber composition sealing gasket, and any impairment of this gasket results in' a leaky valve and possible failure of the tire due to its operation under improper inflation conditions. The high temperatures transmitted to the valve mechanism are harmful to the sealing gasket. Furthermore, the heat transmitted to the metal parts of the valve stem is carried along the valve stem toward the base thereof adjacent to the inner tube. The presence of excessive heat at this point is also objectionable and frequently results in failure of the assembly due to leakage in the region of the valve base. In accordance with the practice of our invention, we provide an insulating medium in the form of rubber composition covering the entire outer surface of the assembled valve stem and cap. Rubber composition, as compared with metal, has relatively high heat resisting characteristics and, consequently, heat transmitted through the cap to vital parts of the valve stem is considerably reduced.

It is among the objects of our invention to provide a valve stem and valve stem cap with a non-metallic covering therefor to resist transmission of heat; to provide a valve stem and cap which, in addition to their primary function, have a secondary seal for inflation pressure and a seal at the margins of the cap to engage the valve stem and prevent mud or other forms of grit from entering with the threaded portion of the valve stem; to provide a cap in which the sealing gasket and outer covering of rubber composition are formed integrally, thus permitting application and vulcanization of the rubber compositions in one operation; and to provide a valve stem and cap which are neat in appearance, smooth in general contour and which includes a cap surface permitting easy manipulation thereof by an operator.

It is a further object of the invention to provide a supporting rim for an automobile wheel having a brake drum located Within and closely adjacent to said rim, and having a pneumatic tire and inner tube mounted on the rim, with a valve stem and cap assembly positioned between the brake drum and supporting rim "and operatively connected with the inner tube, the stem and cap assembly including a layer of rubber composition bonded to the outer surface thereof to form a protective and heat insulating inclosure for the assembly. I

The present application is a divisional from our co-pending application Serial No. 262,694.

7 The above and other objects and advantages will appear more fully in the following detailed description when considered in connection with the accompanying drawing, in which:

Fig. 1 is an enlargedview, in section, of a valve stem cap embodying features of our invention;

Fig. 2 is a similar view, illustrating the valve stem cap in assembly with a valve stem;

Fig. 3 is a transverse view, in section, of a pneumatic tire and wheel assembly, illustrating an application of the invention; and,

Fig. 4 is an enlarged view of a modified form of a valve cap.

Referring to the drawing, and in particular to Fig. 1, We show a metallic valve cap I having threads 2 formed therein for complementary assembly with a valve stem. A conventional gasket 3 of rubber composition is located at the closed end of the cap I for the purpose of forming a seal with the end of a valve stem. A rubber composition 4 completely covers the outer surface of the cap I and is bonded thereto during the vulcanizing operation. The bevelled marginal edge 5 of the rubber composition covering 4 forms a free portion extending beyond the marginal edge 6 of the metal cap I. The purpose of the laterally flexible free edge 5, as more particularly shown in Fig. 2, is to form a sealing engagement with the rubber composition of a valve stem 1, while at the same time being yieldable so as not to interfere with the seal formed between the sealing gasket 3 and the end of a threaded portion 8 of the valve stem. In other words, the sealing gasket 3 engages tightly with the end of the thread portion 8 of the valve stem, but because it is yieldable it readily allows the free edge 5 to be adjusted into association with the valve stem 1.

The application of the invention as shown in Fig. 3 illustrates an assembly including a pneumatic tire having a carcass 9, inextensible bead members l and H, and a tread 12. An inner tube 13 is mounted within the tire, and the unit is assembled on a rim M. A wheel flange I supports the rim l4 upon a wheel hub (not shown). A brake drum I6 is secured to the wheel flange [5. The valve stem 1 includes a valve stem base I! which is vulcanized to'the inner tube l3. Within the rubber composition of the valve stem 1 is a bendable, tubular metallic core I8 extending throughout the length of the valve stem and terminating with the flange l9 at the base of the stem. The rubber composition of the valve stem also aids in insulating the core I8 from the heat generated by the brake drum. A flap 20, interposed between the inner tube l3 and rim l4 and between the valve stem base I! and the rim [4, completes the assembly.

From the illustration, Fig. 3 it is apparent that there is very little clearance between the rim l4 and brake drum 16 for accommodating the valve stem 1. As a result, it is difiicult to maintain the stem in position out of contact with the brake drum or its associated parts. Even when the valve stem is properly positioned relative to the wheel assembly, it frequently moves under ordinary operating conditions and contacts with the brake drum. The detrimental effects of the elevated temperatures to which the valve stem parts become subjected through heat transmission from the brake drum is apparent when it is considered that the operating temperature of the brake drum frequently exceeds 400 Fahrenheit. While this temperature is sufficient to scorch and impair the rubber composition at vital points, such as the valve mechanism seal and valve base assembly, outside of slight physical changes it has no detrimental effect upon the rubber composition when used merely as a covering.

In Fig. 4 is shown a modification of the invention, illustrating a tubular member 2| having internal threads 22 for complementary association with the threaded portion of the valve stem. The upper marginal end 23 of the tubular member 21 is turned inwardly to provide a support for a gasket member 24 located within the tubular member 2|. The outer surface of the tubular member 2| is covered with a layer of rubber composition 25 vulcanized in bonded relation with the member 2!. The partially restricted opening 26 at the upper end of the tubular member 2| permits the rubber composition of the sealing member 24 and of the covering 25 to merge together in a unitary construction. By this arrangement it is possible in a single operation to assemble and vulcanize both members 24 and 25 in bonded relation with the tubular member 2|. Free edge 21, forming a part of the covering 25, extends beyond the edge 28 of the tubular member 2|, thus permitting an adjustable seal of the free edge 21 with the valve stem and of the sealing member 24 with the end of the valve stem.

As thus shown and described, we have provided a simplified form of valve stem and cap construction which is economical of manufacture and which, when forming a part of the tire and wheel assembly, lends itself as a safety feature in preventing tire failures.

It is to be understood that the invention is susceptible to those modifications which appear obvious and which appear within the scope of the appended claim.

Having thus described our invention, what we claim and desire to protect by Letters Patent is:

The combination of a supporting rim, a pneu matic tire and inner tube mounted thereon, a brake drum located within and closely adjacent said rim, securing means for fixedly retaining said drum in position relative to said rim, and a valve stem and cap assembly positioned between said drum and supporting rim and operatively connected with the inner tube, said stem and cap assembly including a layer of rubber composition bonded to the outer surface thereof to form a protective and heat insulating enclosure for said assembly.

ERNST EGER. RAYMOND F. TERNES. 

